I would like to find a Park and Ride in the Southeastern area of Paris, as far out as reasonable. I will need to park for 48 to 60 hours and would like to be as near public transportation as possible
So the South eastern area of Paris means the 12th district. It is located next to the Bois de Vincennes where you can easily park you car for free and leave it there for few days. Then you can easily take the bus and the metro from there. If you driving, get out the ring (Boulevard Périphérique) at Porte Dorée or Porte de Vincennes. Then drive straight to the Bois de Vincennes and park once you find a spot for your car. Just make sure that it isn't written "Payant" on the ground.